This invention relates to a movable tape guide device especially suitable for use in an inclined or helical-scan type magnetic recording and reproducing device or a helical-scan type video tape recorder.
As disclosed, for example, in U.S. Pat. No. 3,388,221 to Delmar R. Johnson et al. dated June 11, 1968, in a helical-scan type video tape recorder, for the purpose of controlling the tape wrapping angle of a magnetic tape, two tape guide members are disposed adjacent to a head drum.
Especially in a video tape recorder of the type standardized pursuant to the Society of Motion Picture and Television Engineers Inc. (SMPTE-C), since the tape is wrapped about the entire periphery of the head drum, i.e. for 344.degree. (known as Omega wrap) the two tape guide devices are extremely closely disposed not only to the head drum but also relative with each other. For example, the spacing between the tape guide devices and the head drum is about 0.2 mm and that between the two tape guide devices is about 1.5 mm. For this reason, it is extremely difficult to wrap the tape about the head drum at the time of loading the tape, which is one of the disadvantages of the prior art video tape recorders of the type described above. The detail of the SMPTE-C type is described in a David K. Fibush paper entitled SMPTE Type C Helical-Scan Recording Format, SMPTE, Vol. 87, pages 755-760, Nov. 1978.
As disclosed in Japanese Patent Publication No. 25243/1978 dated June 26, 1978 (inventor Nagata), when the tape guide devices are moved away from the head drum, the tape can be readily wrapped, for facilitating interchange of video tape, but it is necessary to make very small the spacing between the tape guide devices and the head drum, 15 microns, for example. Accordingly, it is difficult to construct the tape guide devices to be movable and when the tape guide devices are constructed to be movable, high accuracy of machining of the component parts is necessary, thus increasing the cost of manufacturing.